Born in 1937, Mattson was a veteran US Army paratrooper before becoming a top motion picture stuntman for more than 40 years. He began doing stunt work on the Irwin Allen-produced television series Voyage to the Bottom of the Sea, from 1964 through 1968, and Land of the Giants, from 1968 through 1970. He would go on to perform stunts in two of Allen's films, The Poseidon Adventure in 1972 and The Towering Inferno in 1974.